In the case of vehicle seats with belt integration, that is to say vehicle seats in the case of which some or all fastening points of a safety belt system are connected to the vehicle seat, the fact that a safety belt or a belt retractor mechanism of the safety belt is connected to the backrest upper edge of a backrest of the vehicle seat has the effect that, in the event of a crash, considerably higher loads act in a fitting, which serves as a backrest adjuster, than in the case of vehicle seats without belt integration. The required high outlay for development for fittings designed specifically for such high loads is, from an economic aspect, often opposed to the normally low production numbers of such belt-integral seats. Since the strength requirements for fittings in belt-integral seats are often in the range of twice the strength of fittings for conventional seats without belt connection to the backrest, it is normally the case that, for belt-integral seats, two identical fittings are connected in parallel to form a double fitting and are fixedly connected to one another in order to thereby provide, in an economical manner, a fitting for a belt-integral seat. DE 35 29 887 A1 has disclosed a double fitting of said type.
In the case of two single fittings being connected in parallel and rigidly connected to one another to form a double fitting, the loads in the event of a crash are distributed between the two interconnected fittings, such that the strength requirements are met. It is however sought for the mechanisms in the two fittings, despite the rigid connection to one another, to also satisfy functional requirements with regard to an elimination of play during driving operation and with regard to maximum admissible actuation moments during adjustment, such as is conventional in the case of single fittings. For this purpose, however, no satisfactory solution which satisfies these functional requirements is known from the prior art.
In the case of continuous backrest adjusters being used, that is to say classic tumble mechanism fittings with wedge eccentrics for elimination of play, which are also referred to as geared fittings and which are known for example from DE 10 2011 012 076 A1, it is known for component tolerances to be compensated by way of a wedge eccentric system comprising two oppositely spring-preloaded wedge segments. Here, the effective axis spacing of the two gearing parts relative to one another automatically adjusts, by way of the wedge movement, to the extent required for the elimination of play. During the course of the expected overall fluctuation of component tolerances of the individual parts of a single fitting, it is possible with this technology to economically produce play-free and nevertheless easily adjustable single fittings. In the case of an absolutely rigid connection of two individual fittings to one another, that is to say a rigid connection of two first fitting parts to one another and of two second fitting parts to one another, in the case of which an identical axis spacing dimension is fixed to an identical dimension for both fittings, the effectively required axis spacings of the two interconnected fittings can no longer be adjusted independently of one another. As a result, it is necessary for further, relatively high demands to be placed on the tolerance compensation capability of the wedge eccentric systems, or the admissible tolerance range of the individual parts must be restricted to a greater extent than is necessary for individual fittings. Both possibilities entail additional outlay in the production process, be it in the production of the individual parts, in the need for other individual parts to be assembled together or in the joining process during which the individual fittings must be connected to one another in a precise alignment relative to one another.
DE 10 2006 000 532 A1 has disclosed a double fitting having two interconnected fittings, wherein each of the two fittings has a first fitting part and a second fitting part which are in toothed engagement with one another. One of the two fittings has a wedge eccentric, which is arranged between the first fitting part and the second fitting part, for the elimination of play in the toothed engagement. The other of the two fittings has, instead of a wedge eccentric, a support element which is arranged between the first fitting part and the second fitting part and which has a smaller eccentricity than the wedge eccentric of the other fitting. During the normal operation of the double fitting, only the wedge eccentric but not the support element bears load. After a limited deformation in the double fitting, such as arises in particular in the event of a vehicle collision, the support element additionally supports the toothed engagement.
DE 10 2004 049 114 B4 discloses a double fitting which comprises a first fitting part, a second fitting part and an eccentric which are each arranged on a common axis of rotation. The first fitting part is formed from two first fitting part elements. The second fitting part is formed from two second fitting part elements.